When manufacturing a structural body, such as a heat exchanger, which employs an aluminum alloy material as a constituent member, it is required to bond the aluminum alloy materials to each other or to bond the aluminum alloy material to another different type of material. Various methods are known as bonding methods for the aluminum alloy material. Among the various methods, a brazing method (hard soldering method) is used in many cases. The brazing method is often used in consideration of, e.g., an advantage that strong bonding can be obtained in a short time without melting a base material. As methods for manufacturing a heat exchanger, etc. by employing methods of bonding the aluminum alloy material with the brazing, there are known, for example, a method of using a brazing sheet on which a brazing filler metal made of an Al—Si alloy is clad, a method of using an extruded member coated with a powdery brazing filler metal, and a method of assembling various members and then additionally applying a brazing filler metal to portions that are to be bonded (Patent Documents 1 to 3). Moreover, “Chapter 3.2 Brazing Alloys and Brazing Sheets” in Non-Patent Document 1 explains the clad brazing sheet and the powdery brazing filler metal in detail.
Up to date, various brazing methods have been developed in the field of manufacturing of a structural body using an aluminum alloy material. In relation to vehicular heat exchangers, for example, when a fin member is used in a single layer, there have been utilized a method of using a brazing sheet made of a tube material sheet on which a brazing filler metal is clad, and a method of additionally coating Si powder or a Si-containing brazing metal over the tube material sheet. On the other hand, when the tube member is used in a single layer, there has been utilized a method of using a brazing sheet made of a fin material sheet on which a brazing filler metal is clad.
Patent Document 4 discloses a method of employing a single-layer brazing sheet instead of the above-mentioned clad brazing sheet. That method proposes the use of the single-layer brazing sheet for a heat exchanger as a fin member and a tank member of the heat exchanger. According to Patent Document 4, a desired shape is held by adjusting an amount of Si to be added and a brazing temperature. In the fin member that is thinner than the tube member and/or the tank member, however, the disclosed method is not satisfactory as a method for maintaining the desired shape while ensuring sufficient brazing performance.